diff options
| author | Steven Rostedt <rostedt@goodmis.org> | 2008-05-12 21:21:02 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2008-05-23 22:01:34 +0200 |
| commit | 2bb6f8d6389cbfadd657e7dc069f6986abf35e4f (patch) | |
| tree | 894c84bdec4c716b1e16c60e2ab2a1ab198ac11d /kernel/trace/ftrace.c | |
| parent | a4feb8348b62fe76a63cdb5569f5c920f5283c06 (diff) | |
| download | lwn-2bb6f8d6389cbfadd657e7dc069f6986abf35e4f.tar.gz lwn-2bb6f8d6389cbfadd657e7dc069f6986abf35e4f.zip | |
ftrace: use raw_smp_processor_id for mcount functions
Due to debug hooks in the kernel that can change the way smp_processor_id
works, use raw_smp_processor_id in mcount called functions (namely
ftrace_record_ip). Currently we annotate most debug functions from calling
mcount, but we should not rely on that to prevent kernel lockups.
This patch uses the raw_smp_processor_id to prevent a recusive crash
that can happen if a debug hook in smp_processor_id calls mcount.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/trace/ftrace.c')
| -rw-r--r-- | kernel/trace/ftrace.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 40f64f7cd850..af5ad8949abb 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -267,6 +267,7 @@ ftrace_record_ip(unsigned long ip) unsigned long key; int resched; int atomic; + int cpu; if (!ftrace_enabled || ftrace_disabled) return; @@ -274,9 +275,15 @@ ftrace_record_ip(unsigned long ip) resched = need_resched(); preempt_disable_notrace(); - /* We simply need to protect against recursion */ - __get_cpu_var(ftrace_shutdown_disable_cpu)++; - if (__get_cpu_var(ftrace_shutdown_disable_cpu) != 1) + /* + * We simply need to protect against recursion. + * Use the the raw version of smp_processor_id and not + * __get_cpu_var which can call debug hooks that can + * cause a recursive crash here. + */ + cpu = raw_smp_processor_id(); + per_cpu(ftrace_shutdown_disable_cpu, cpu)++; + if (per_cpu(ftrace_shutdown_disable_cpu, cpu) != 1) goto out; if (unlikely(ftrace_record_suspend)) @@ -317,7 +324,7 @@ ftrace_record_ip(unsigned long ip) out_unlock: spin_unlock_irqrestore(&ftrace_shutdown_lock, flags); out: - __get_cpu_var(ftrace_shutdown_disable_cpu)--; + per_cpu(ftrace_shutdown_disable_cpu, cpu)--; /* prevent recursion with scheduler */ if (resched) |